CVE-2026-82035
Received Received - Intake

Path Traversal in PyMuPDF via Malicious BaseFont

Publication date: 2026-09-14

Last updated on: 2026-09-14

Assigner: VulnCheck

Description
PyMuPDF through 1.28.2, fixed in commit b2c8f3a, contains a path traversal vulnerability in the font branch of extract_objects() in src/__main__.py, where the output filename is constructed by joining a document-controlled BaseFont name directly onto the user-supplied output directory without stripping path separators or dot-dot sequences. Attackers can supply a crafted PDF, EPUB, XPS, or FB2 file with a BaseFont name containing encoded path separators that decode to ../ sequences or absolute paths, causing arbitrary file writes outside the intended output directory without requiring authentication or elevated privileges.

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Meta Information

Published
2026-09-14
Last Modified
2026-09-14
Generated
2026-09-14
AI Q&A
2026-09-14
EPSS Evaluated
N/A
NVD
CVE-2026-82035
EUVD
EUVD-2026-77764

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
pymupdf pymupdf From 1.28.2 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

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Executive Summary

PyMuPDF through 1.28.2 has a path traversal vulnerability in the font branch of extract_objects(). The issue occurs when constructing an output filename by joining a document-controlled BaseFont name directly to a user-supplied output directory without sanitizing path separators or dot-dot sequences. Attackers can exploit this by embedding encoded path separators in a BaseFont name that decode to ../ or absolute paths, enabling arbitrary file writes outside the intended directory.

Detection Guidance

Detecting this vulnerability requires checking for vulnerable versions of PyMuPDF and analyzing PDF files for malicious BaseFont names. Inspect installed PyMuPDF versions with pip show pymupdf. Scan PDFs for BaseFont names containing path traversal sequences like ../ or absolute paths using tools like pdfinfo or custom scripts.

Impact Analysis

This vulnerability allows attackers to write files to arbitrary locations on your system by tricking you into processing a maliciously crafted PDF, EPUB, XPS, or FB2 file. This could lead to overwriting critical system files, installing malware, or gaining unauthorized access to sensitive data without needing authentication or elevated privileges.

Mitigation Strategies

Upgrade PyMuPDF to version 1.28.3 or later, which includes the fix in commit b2c8f3a. Avoid processing untrusted PDF, EPUB, XPS, or FB2 files until patched. Implement strict input validation for BaseFont names in your applications.

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